THE PLT OF A PA28 VIOLATED AN ADIZ BECAUSE OF COM DIFFICULTIES.

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I CONTACTED THE DCA FSS TO GET A FORECAST; AND BEFORE THE FLT I CONTACTED THEM AGAIN TO GET A PREFLT BRIEFING AND TO FILE AN ADIZ FLT PLAN. ALTHOUGH I AM NEW TO THE DC AREA; I BRIEFED MYSELF CAREFULLY BEFORE FLYING INTO THE ADIZ; AND WAS ABLE TO FLY INTO GAI. BEFORE INITIATING MY TAXI I CONTACTED APCH AND WAS TOLD THAT THERE WAS NO FLT PLAN ON FILE. I THEN SHUT DOWN; AND CONTACTED LEESBURG AGAIN TO FILE MY FLT PLAN THE SAME AS I HAD DONE PREVIOUSLY. THAT DONE; I STARTED UP; CONTACTED PCT APCH; AND WAS TOLD TO XMIT A DISCRETE XPONDER CODE AND MONITOR 125.52. I TUNED THE XPONDER AS DIRECTED; AND DEPARTED GAI. ONCE AIRBORNE AND AWAY FROM THE TFC PATTERN I TUNED MY RADIO AS DIRECTED BY PCT APCH AND LEFT THE VICINITY OF HDG W. ABOUT THE TIME WE REACHED THE OUTER LIMITS OF THE ADIZ I REALIZED THAT MY RADIO HAD GONE QUIET; AND DID NOT BELIEVE MYSELF TO BE STILL IN CONTACT WITH PCT APCH. I CALLED PCT APCH; BUT DID NOT RECEIVE A REPLY. I IMMEDIATELY REVERSED COURSE ON A HDG AROUND THE DCA CLASS B AND TOWARDS GAI. SOON THEREAFTER A MIL HELI WAS SPOTTED OFF OUR STARBOARD WING. THE HELI DISAPPEARED FROM VIEW BEHIND THE ACFT. FINALLY; I WAS ABLE TO ESTABLISH 2-WAY RADIO CONTACT WITH PCT APCH. (I HAD BEEN RECEIVING XMISSIONS RIGHT AFTER MY TURN AROUND.) I WAS DIRECTED TO SQUAWK THE XPONDER CODE I HAD BEEN USING; AND WAS CLRED TO GAI WITH THE APPROPRIATE FREQ CHANGE. AFTER LNDG I REALIZED SOMETHING WAS AMISS AS THE HELI LANDED AND 4 TSA OFFICERS APCHED. I IDENTED MYSELF AS THE PLT; AND COOPERATED WITH THEM FULLY. THEY WERE COURTEOUS AND PROFESSIONAL; AND REQUESTED THAT I CONTACT THE TRACON AND FURNISHED ME WITH THE APPROPRIATE TELEPHONE NUMBER. WE SECURED THE ACFT AND DEPARTED. ON THE WAY BACK TO MY HOTEL I CONTACTED PCT TRACON AND ANSWERED ALL OF THEIR QUESTIONS.